Process for producing lubricating oils



.zo loro! ...rui

PROCESS FOR PRODUCING LUBRICATING OILS Patented Jim'. 21, 193.6v

PATENT yll`2,023,361

oFFicE i rnocsss Fon Pnoilggma Luarca'rmo.

John V. Starr and David F. Edwards, Elizabeth, N. J., assignors toStandard Oil Development Company, a corporation of Delaware.

' Application :une zo, 1931, seran No. 545,693

2 Claims. (Cl. 196-79) This invention relates to a' process forproducing nished lubricating oils of high color and good cast from alubricating oil stock treated with a selective solvent. 'Ihe .inventionwill be fully understood from the following description read y incommotion with the drawing, the sole gure of which is a diagrammaticside elevation, partly in section, showing one form of the apparatusused for carrying out the invention.

When producing lubricating oils .by extraction with selective solven'tssuch as phenol, aniline, furfural, etc., it is customary to subject theraffinate to distillation or to agitate it with a suitable washingmedium in order to remove the solvent from the' treated oil. 'Ihegeneral appearance of the lubricating `oil thus obtained from anoriginally low grade distillate is distinctly inferior and .necessitatesa iinishing procedureof some kind. The object of the present inventionis to provide a iinishing procedure whereby the solvent is separatedfrom the raflinate and vat the same time 'a fln'ished lubricating oil ofany desired viscosity is 'obtained possessing high color and excellent'appearance' when viewed in reflected light. After treatingmineral oil or a distillate with selective solvents the treated oillayer usually contains from to 20% of the solvent depending on thesolvent employedand the temperature of the treat. We have found that bymixing a small quantity, say 5/8 lb. to 1 1b. per gallon of adsorbentclay. such as fullers earth or an acid A treated er activated clay,withthe. treated oil,

subjecting the mixture of oil and clay to dis` tillation so as to removethe solvent with the lighter oils and subsequently separating the clay.from the residual oil, not only the separation of the selective solventfrom the lubricating oil is obtained, but simu1taneously,a finishedlubricating oil product is produced which has excellent colr and cast.'I'he distillation may be carried out either in a shell still or in apipe still or in a combination of a shell still and a pipe still or twopipe stills, as will be understood hereinafter.

In some cases it may be desirable or economical toY recover part oi'vthe solvent from the treated oil by means other than distillation, suchas, for example, by washing, or it may be economical to distill olf themaior portion (say 90%) or even more of the solvent in a shell stillthenadd theclay to the residual oil and submit thelatter toldistillation in a pipe still in the presence oi' clay.

The preferred operation, however, is the following: 55.

. The vraiiinate containing some solvent ismixed withv agitation withthe necessary quantity oi' fullers earth or an activated clay and theslurry thus obtained is passedthrough heat exchangers and thenv throughthe heating coil of a pipe still where it is heated to a .temperaturesuiiiciently 5 high to vaporize most of the solvent. The hot oil andclay mixture is then discharged into the vaporizing zone of abubbletower held under substantially atmospheric pressure. The solventwill be taken off as an overhead product from the tower, and iscondensed and returned to storage for further use. The bottoms from theatmospheric tower are further heated by passage through a separateheating coil placed in a furnace or by other suitable means to such atemperature as to vaporize the lighter portions of the oil and insurelthe removal of any remaining solvent.l The hot bottoms containing theclay are then flashed into the vaporizing 'zone of a bubble towerheldunder high vacuum. The'remaining solvent together with some lightoil is obtained as overhead product from the vacuum tower, spindle oilsor light motor oils are taken out as upper side stream, heavier motoroils as lower side stream and cylinder oil or heavy motor oil containingspent clay is ywithdrawn as bottoms, cooled and passed through a filterpress to remove the clay. The procedure may be varied to produce oils ofany desired viscosity. The`apparatus for this preferred operation isshown in the drawing. v

Referring now to the drawing, numeral I designates an oil storage tank,2 a'. treater for treating the oil with a selective solvent, 3 thestorage tank for the extract and 4. 'the storage tank for the treatedoil. The hopper 5, mixing tank 6 and mixer 'I serve for the admixtureofdecolorizing clay to the treated oil. Pump 8, heat exchangers 9, IIIand .tube still Il, serve for passing and heating the oil clay slurryinto the vaporizing and fractionating tower I1. The overhead product(treating solvent) is removed through line- I3. condensed in'condenserI4 and stored in tank I5 from which it may be pumped by means of pump I8into treater 2. The residue of distilla- I tion is removed from tower I2through line Il 45 and passed by means of pump I8 through tube still I9and line 20 provided with the Vpressure reduction valve into the vacuumtowerZI. The overhead product leaves the vacuum tower, through line 22and is condensed in condenser 23. Means such as vacuum steam jet pumps24 or any other known means are provided for maintaining the necessaryvacuum.' Lines 25 and 26 serve for removing' the side streams throughheat exchangers I and I0. respectively. The residue 5I and is pumped bymeans of pump 28 through.

` each case removed as before.

' .The b`ulk ofthe rainate with the 12% phenoll from the vacuumtowerleaves through line 21 cooler 29 and filter press 30 to separate thespent clay from the treated reslduum.

ess.

A crude lubricating distillate from Colombia having gravity of 21.8A..P. I., viscosity of 63 at 210 F. and viscosity index of 43(determined by the method described in the article of E. W. Dean and G.H. B. Davis, Chemical and Metallurgical Engineering, volume 36, No. 10,October 1929), was

treated with 50% by volume of 100% phenol at 108 F. After agitation forabout ten minutes the mixture was allowed to stratify and the extractlayerwithdrawn. Five additional dumps of phenol each 50% by volume ofthe oil beingk treated were applied and the extract layers in Arafilnate yield of63.7% was obtained. A sample of the rainate whichshowed 12% phenol was dephenolized by distillation, yieldingdephenolized oil 56% of charge. The phenol free oil had a gravity of27.7 viscosity of 59 seconds Saybolt at 210 F. a viscosity index of 88,but low Robinson color.

content was placed in an agitator heated at 11G-120 F. and mixed with1/2 lb. per gallon of an activated adsorbent clay. The oil clay slurrywas then fed through a heating coil where the temperature was raised to557 F. and flashed into the vaporizing chamber of Va bubble tower, keptsubstantially under an absolute pressure of 20 mm. mercury.Substantially. all of the remaining solvent was taken overhead togetherwith a relatively small amount of gas oil, a portion of the overheadbeing returned to the tower as reflux. .The bottoms amounting to 78% ofthe charge were withdrawn, partially cooled (to about Qualitative testsin the bottoms showed no phenol present.

As a second example of carrying out our invention samples of the phenoltreated Colombian oil described above were partially dephenolized ,l bywashing with NaOH solution, the major portion (about of the phenol beingwashed out. The residual oil amounting to about 89% of the originalrainate was blown bright at F., mixed with clay at about 120 F., passedthrough the heating coil of a pipe still where it was heated to atemperature of 675 F., and flashed into the vaporizing zone of thebubble tower held at an absolute pressure of 17-18 mm. of imercury, aportion of the overhead being returned to the tower as reflux.

Two similar experiments were carried out. In one case the sampleof'residual oil from the first still was mixed with 1A lb. per gallon ofacid treated clay and distilled in a pipe still, 83% being takenoverhead and 17% vobtained as bottoms.` In the other case 1,/4 lb. pergallon of finely powdered A ttapulgus clay was added to the oil anddistilled in the pipe still to obtain 80.3% of overhead products and19.7% of bottoms. The

The following examples will illustrate our proci bottoms of bothexperiments were cooled and filtered, yielding cylinder oils with thefollowing inspection:

In both cases, the color stability as tested by 15 maintaining the oilat a temperature of 212 F.` for sixteen hours, was very good, and thegeneral appearance of the yoils viewed by reflected light showed adesirable olive green cast. The overhead products were rerun givingSpindle oil, light machine oil and motor oil of good quality.

In the following claims, the expression selective solvent is meant todesignate solvents of the type of phenol, aniline, furfural, etc., whichwhen brought in contact with the oil, selectively absorb certainundesirable constituents of unsaturated and/or aromatic character. Theexpression is not meantq to include agents which have a chemical actionon the constituents of the oil such as, for example, sulfuric acid,which not only absorbs certain constituents, but also causespolymerization and sludge formation, or other treating agents such asaluminum chloride, zinc chloride, iron chloride, and' solutions thereof35 which cause polymerization or condensation reactions with certainconstituents of the oil.

This invention is not to be limited by any theory or by the examplesgiven by way of illus-v tration, but only by the appended claims inwhich 40 it is our intention to claim all inherent novelty of ourprocess.

We claim:

1. Process of preparing lubricating oil from a lubricating oil stockwhich comprises agitating the stock with a selective solvent, separatingthe extract layer from the rainate layer, subjecting the ramnate layerin the presence of the absorbed selective solvent which it containsy atthe time of its separation from the extract layer to fractionaldistillation in the presence of an adsorbentclay, and removing theadsorbent clay 'from the distillation residue.

2. The process of preparing lubricating oil from a. lubricating oilstock which comprises treating said stock by agitation with'a selectivesolvent, separating the extract layer from the raffinate. layer, mixingsaid raffinate layer with an adsorbent clay in the presence of theabsorbed se- 60 lective solvent which it contains at the time of itsseparation from the extract layer to obtain a slurry, passingthe slurrythrough an elongated narrow heating zone into an enlarged combinedvaporizing and fractionating zone held under ate5 mospheric pressure,removing substantially all of the solvent and a part of the oil asdistillate, passing the' residue through a second elongated narrowheating zone, discharging the heated residue into an enlarged combinedvaporizing and fractionat- 70 ing zone held under vacuum to obtain atleast one distillate and a second residue, and separating the clay fromthe second residue.

JOHNI V. STARR.

